This project extends our past work on tactile pathways of the spinal cord to an investigation of the thermesthetic systems of the cord in the monkey. We will seek to determine whether hindlimb afferent fibers in the anterolateral quadrant are necessary for temperature discrimination, or whether this discrimination may be mediated by other fiber systems as well. Monkeys will be restrained in a chair before a response panel with two levels. They will be trained to respond to one lever when a Peltier thermode attached to the leg is cooled, and to other lever when the thermode is heated. Both legs will be tested. Upon completion of training, the animals will undergo surgical section of various parts of the spinal cord at the thoracic level, such as the anterolateral and dorsolateral quadrants and the dorsal columns, alone or in combination, unilateral or bilateral. Any animal showing post-operative deficits in thermal sensitivity will be retested again over several months. Animals retaining the capacity for thermesthesia will also undergo parietal cortex ablations. The behavioral and anatomical data will be compared to determine which, if any, spinal cord pathways serve as an alternate to the traditional spinothalamic system in mediating temperature discrimination.